The following description relates to a method of motion estimation and an image processing apparatus using the same.
Motion estimation technology is technology that obtains a motion vector by finding movement of an object or a background using two consecutive frames of video. The motion estimation technology is one of the important technologies which are used in a variety of image processing fields such as video compression, three-dimensional (3D)-noise reduction, de-interlacing, frame rate conversion (FRC), and the like.
A variety of motion estimation technologies from full search technology to fast search technology have been developed. Video compression is used to reduce redundancy between consecutive frames, and therefore the main purpose of the video compression is to find a motion vector in which a motion compression error is minimized rather than find accurate motion information of an actual object. The main purpose of FRC is to find accurate motion information of an actual object or a background.
Motions of a moving object in a video may be classified into a case in which the object performs decelerated or accelerated motion with acceleration, or a case in which the object performs motion at constant velocity. However, even in the case in which the object performs accelerated motion, when the motion except for the beginning and the end of the motion is divided by a reasonably short time interval, the motion may be classified into motion nearly close to motion at constant velocity, and portions classified in this manner may occupy a large portion of the motion.
In an example in which an object displayed in an image performs motion at constant velocity during a total of 8 frames from frame 0 to frame 7, motion estimation of a frame unit is performed a total of seven times in the frames 0 and 1, frames 1 and 2, frames 2 and 3, frames 3 and 4, frames 4 and 5, frames 5 and 6, and frames 6 and 7. When using the result of motion estimation of a previous frame and the result of local motion estimation prior to a corresponding frame while performing motion estimation of a frame unit, the reliability of motion estimation may be improved. In particular, in a case in which an object uniformly performs motion at constant velocity without acceleration or deceleration, the motion vector obtained over several frames may be the same as the motion vector of an actual object or have only a small difference therebetween, and therefore it is possible to obtain the result that the estimated motion vector is converged onto the motion vector of the actual object.